I've had my Up for a few years now and still on version 1.2 as I'm reluctant to change anything as it always worked just fine.
I also have taken apart the nozzle assembly and had to clean all tubes and the nozzle, so I am familiar with this problem. What I am experiencing now is the the platform just comes to a halt, at the raft stage and nothing happens. I don't think it has anything to do with the nozzle, as I've had a clogged nozzle before, and the platform just keeps going without extruded plastic. This time the whole machine just stops.
Any clues as to what I can check?
I've also rebooted my computer as well as the UP and it always starts out fine, and then just stops.

Help please.
Ken

DId you open the UP! inspector and check for any error messages and what not?

No, didn't know about that function, but I think I found the problem with not
the correct temp of the platform. I replaced the heater with a spare I had and
now it's working again.
Thanks